This paper presents the ACE modular framework (Action-Causality-Ethics), a modular and declarative logic-based framework for representing and applying multiple ethical principles. We clearly separate modeling concerns about dynamics and ethics, using reification to explicitly represent generic metarules to be contrasted with specific domain knowledge. This allows us to formalize ethical principles as methods for ethical assessment of actions and plans and specify what additional domain information are needed for each of them in addition to the factual description of the unfolding of events. The architecture presented here is based on an action model allowing concurrency and multiple agents and we discuss how this affects the ethical assessment process and allows precise modelling of omission.